Welcome to the forum!
Lying that you are ok is what we do when we are depressed. We do not want to be a burden to anyone.
This in itself is not shameful.
Your old memories, how much of them do you exaggerate? Catastrophize? It is so easy to do that when we have guilt deep inside. Then we find out that the people we think we hurt, never gave the incident a second thought.
Can go to a therapist or a Psychiatrist? Sounds like you may be dealing with more than just depression.
I don't know what, I am not a professional, however the guilt and shame,I think indicates something more.
It was extremely brave of you to post here. You are not alone, and we do not judge. Many of us have gone, or are going thru what you are. The emotions are common to many people and you can be helped.
To give you an answers the cause of the feelings, is not possible, there are too many, this why I suggested a professional for you to see.
Keep writing this a great skill for getting out anger and shame. Here is a link to a free site that may help.https://www.mindful.org/?s=shame+and+guilt
Peace and strength
Moderator - Depression
"...when the gift of sight is cause enough for jubilation."
Billy Collins from the poem. HIGH
DX: reverse Trigeminal Neuralgia;Cluster headaches; Atypical face pain;Hemicrania Continua; Complex Migraines: raynauds;Complex PTSD; recurring MDD,disassociative disorder with psychotic features. Laryngopharyngeal Reflux Disease [LPR]